Various devices are available for converting solar radiation into either thermal or electrical energy. Examples of devices for converting solar radiation into thermal energy are solar water heaters, solar cookers, solar boilers, thermal mass systems, and systems that heat a thermal working fluid. Examples of devices for converting solar radiation into electrical energy are photovoltaic cells, thermovoltaic cells, and thermal engines, such as a Sterling engine, which use a thermal working fluid to move an apparatus that is configured to generate electricity. Often it is desirable to focus or at least concentrate solar energy flux in order to improve the efficiency of devices that are used to convert solar radiation into thermal or electrical energy. Because solar energy arrives on earth in light beams that are essentially parallel, a mirror having a parabolic shape is traditionally a preferred device for collecting and concentrating solar energy. However, manufacturing parabolic-shaped mirrors is generally difficult and expensive. What are needed therefore are more cost-effective solar collectors.